A motor vehicle door lock apparatus described in PTL 1 receives a remote control signal transmitted from a transmitter carried by a user to lock or unlock a door of a vehicle and executes a door locking (lock) operation or a door unlocking (unlock) operation according to the received remote control signal, informing the user that the required operation is completed by emitting a buzzing sound from a buzzer or flashing a lamp.
A motor vehicle door lock apparatus described in PTL 2 authenticates a portable device that a user carries by transmitting and receiving a signal between the portable device and itself and executes a door unlocking operation when a hand of the user moves nearer to a door of the motor vehicle with the portable device authenticated on the understanding that the user intends to unlock the door in the case where the door is locked, whereas in the case where the door is unlocked, the motor vehicle lock apparatus executes a door locking operation on the understanding that the user intends to lock the door.